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Scientists are getting a better understanding of smoker's cravings for cigarettes.

A new study in the Journal of Neuroscience measured the brain activity of people as they watched actors smoke in a movie.

Participants were smokers and non-smokers. Watching the smoking on screen triggered the same brain activity involved in planning to actually smoke a cigarette. Researchers say that shows a connection to the brain's reward system.

The one limitation to the study: Researchers say they did not follow participants to see whether they actually lit up their own cigarette afterwards.